Enhance Herbicide Efficacy with Spray Tank Water Conditioning

WEED MANAGEMENT

Darcy M. Lepine

8/28/20243 min read

a close-up of some plants
a close-up of some plants

Water is more than just a carrier for herbicides; it's a critical component that can significantly impact their effectiveness. Agricultural spray tank water conditioning is essential for maximizing herbicide efficacy, especially when dealing with hard water or unfavorable pH levels. This article delves into how additives like ammonium sulfate, fulvic acid, and non-ionic surfactants improve herbicide performance. We'll also explore the optimal tank water pH for various common herbicides and address misconceptions about pH levels in weak acid formulations.

The Role of Water Conditioning in Herbicide Efficacy

Water quality directly influences the performance of herbicides. Factors such as pH, hardness, and mineral content can affect herbicide stability and absorption by plants.

  • pH Levels: Extreme pH levels can degrade certain herbicides or reduce their uptake by target weeds.

  • Hardness: High levels of calcium, magnesium, and iron can bind with herbicides, making them less available for plant absorption.

  • Mineral Content: Dissolved minerals can interact with herbicides, reducing their effectiveness.

Ammonium Sulfate (AMS) in Water Conditioning

How AMS Enhances Herbicide Uptake

Ammonium sulfate is a common water conditioner that improves herbicide efficacy by:

  • Binding Hard Water Cations: AMS binds with calcium, magnesium, and iron ions, preventing them from interacting with the herbicide.

  • Enhancing Absorption: The ammonium ion can facilitate better herbicide uptake by plants, particularly with glyphosate and other weak acid herbicides.

Application Tips

  • Dosage: Typically added at 8.5 to 17 lbs per 100 gallons of water.

  • Mixing Order: Add AMS to the tank before the herbicide to ensure proper binding of hard water ions.

Fulvic Acid

Benefits

Fulvic acid is an organic acid known for:

  • Chelation Properties: It binds with mineral ions, reducing their interaction with herbicides.

  • Improved Uptake: Enhances the permeability of plant cells, aiding in herbicide absorption.

  • Environmental Safety: Being a natural organic compound, it's environmentally friendly.

Application Tips

  • Dosage: Follow manufacturer recommendations, usually ranging from 8 to 32 ounces per acre.

  • Compatibility: Generally compatible with most herbicides but always perform a jar test to confirm.

Non-Ionic Surfactants

Role in Herbicide Application

Non-ionic surfactants improve herbicide performance by:

  • Reducing Surface Tension: Allows for better spreading and adhesion of the spray droplets on leaf surfaces.

  • Enhancing Penetration: Facilitates movement of the herbicide into the plant tissue.

Application Tips

  • Dosage: Commonly used at 0.25% to 0.5% v/v (volume/volume).

  • Compatibility: Suitable for use with most herbicides, especially when an adjuvant is recommended on the label.

Optimum Water pH for Common Herbicides

Maintaining the optimal pH in your spray tank is crucial for herbicide stability and effectiveness. Below is a chart outlining the ideal pH ranges for some common generic herbicides:

Addressing High pH in Weak Acid Herbicides

The Misconception

Some experts suggest that maintaining a higher pH in the spray tank is acceptable for weak acid herbicides to improve tank mix compatibility with other products.

The Reality

  • Reduced Efficacy: Higher pH levels can lead to the ionization of weak acid herbicides, reducing their ability to penetrate plant cuticles.

  • Hydrolysis Risk: Certain herbicides are prone to alkaline hydrolysis, where they degrade rapidly in higher pH conditions.

The Solution

  • Jar Tests: Performing simple jar tests can identify compatibility issues without compromising the optimal pH for herbicide efficacy.

  • Sequential Mixing: Adjust mixing order and use compatibility agents if necessary, rather than altering pH away from the optimal range.

Importance of pH Optimization

Enhancing Efficacy Combat's Resistance

  • Effective Doses: Optimal pH ensures the herbicide works at its full potential, reducing the likelihood of sub-lethal doses that contribute to resistance.

  • Consistent Control: Proper pH management leads to better weed control, which is crucial in preventing the spread of resistant weed populations.

The Big Picture

  • Objective of the Spray Pass: The primary goal is effective weed control, not just tank compatibility.

  • Long-term Sustainability: Adhering to optimal pH levels supports sustainable farming practices by prolonging the usefulness of herbicides.

Optimizing spray tank water through proper conditioning is a critical step in maximizing herbicide efficacy. Additives like ammonium sulfate, fulvic acid, and non-ionic surfactants play significant roles in enhancing performance. While tank mix compatibility is important, it should not come at the expense of the herbicide's effectiveness. By focusing on optimal pH levels and utilizing simple tests like jar tests, farmers can achieve effective weed control and contribute to resistance management. Remember, the objective is not just to apply herbicides but to ensure they work effectively for sustainable agriculture.

optimal pH for herbicides chart
optimal pH for herbicides chart

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